Suspension polymerisation of a monomer (such as vinyl chloride) typically uses a primary suspending agent. Such primary suspending agents typically help to control the size of the polymer particles and help inhibit coagulation of polymer particles. It is sometimes desirable to be able to make small polymer particles, but some known primary suspending agents do not facilitate the production of small polymer particles. Within this application the term “particle” is understood in its broadest sense and includes non-aggregated particles as well as particles formed from aggregates of polymerized monomer droplets, usually known in the state of the art as “grains”.
Polymers containing carbonyl groups conjugated with carbon-carbon double bonds are known (such as Alcotex® B72, Synthomer (UK) Ltd) and some are used as primary suspending agents. However, some carbonyl-group containing polymers are yellow, and this colouration may not be acceptable to some users.
The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an alternative and/or improved primary suspending agent.